Note that I recommend doing everything (even the prelude campaign) on hard not medium, that way you also unlock 'Can't Touch This'.

Oh, and you have to complete the campaigns in order unless you've done them before (on easy?).Complete the prelude to unlock the Novus campaign.Complete Novus to unlock Heirarchy campaign.Complete Hierarchy to unlock the Masari campaign.

After completing one of the faction's campaigns, you will get the achievement and the next will automatically start. Once available, each campaign will also be available in the campaign menu.